0748

Item 0748

DESIGN: SynchroLite ~ Fuselage - Body - Cockpit - Layout

Outside Helicopter

Del-Mar DH-2A:

Look at Del-Mar Engineering's DH-2A picture in 'Rotary-Wing Aerodynamics' book page 37 for a simple clean cockpit. This is probably very close to what is wanted for the SynchroLite.

Helicycle:

This is close to the ideal design also.

Mini 500:

For sketch and dimensions see; Cockpit dimensions of Mini 500.

Ultrasport:

The cabin width of the 254 is 30".

SynchroLite
January 27, 2005 A thought ~ the slight weight increase of enclosing the engine etc. may be well offset by the reduced drag, particularly during forward flight.

A thought ~ If the engine is to be mounted laterally, the 'lump' in the fuselage for the large sheave might be matched by a 'lump on the other side for the pivot and linkage for the collective lever.

Pictures of Mockup of Original 254 lb Empty Weight UltraLight:

Tube at bottom is a tunnel for flight controls, a structural member and attachment for the tail boom.

Reasons for Cockpit:

To transmit forces between the fuselage and the top of the drive train.

To provide the pilot with some protection from the elements.

For aesthetics.

Drawing: Cockpit to be widened to 28" to 30", so that collective lever etc. is inside. Or even wider, but do not restrict the cooling airflow to the reducer and the engine. Also reduce the headroom. Consider the possibility of fully enclosed with one door.

Sides of top (either side of canopy) to be rolled approximately 80-degrees, from parallel with canopy to vertical. I.e. 80 degree segment. They will have an opposing 80-degree segment to give thickness along these braces. This will give strength and aesthetics. 2" radius for approximately 3" (curved) width. This 'beam will widen out at top and bottom. It will also become thinner at bottom as it flares in to the shell.

Consider bringing the top half of the seat sides in by 1"on both sides.

Consider decreasing width between the widest part of cockpit upper braces by 1" on both sides.

If fuel tank does not have to be so high, then consider lowering the top by 2-3" ~ SynchroLite note only.

The top of the cabin can probably be lower, but on the Dragonfly it might be advantageous to leave it high so that the intermediate/primary reduction is aerodynamically 'hidden' within the fuselage and the top attachment locations between the power train and fuselage are optimized.

A X-section through the cockpit will be fairly parallel to the airflow. Because this airflow has a slower velocity than the airflow seen by the blade, a fatter profile will be more efficient. Therefor make the cocpit X-section profile as close to the NACA 0035 to 0045 as possible.

Side Enclosure:

For enclosing the sides of the cockpit, consider Velcro, 'zip-lock' or zipper around the edge of the cockpit's side openings and flexible plastic sheeting sides, which are attached to the Velcro. There should probably be a few 'hard' attachment points so that a side sheet cannot pull of during flight. If the Velcro seal is complete than a slight air pressure inside the cockpit may hold these two sheet taught and slightly bowed outward. Potential disadvantage:- Plastic may result in distorted and unclear visibility.

Email from Kevin Ryan: kevin@mediacy.com

In regards to the doors, you might look at the CGS Hawk, page 9 onward, (www.cgsaviation.com) for an example of a zippered on door. It's a mixed Dacron and clear plastic sheet (thin Lexan, I believe) that zips on the side of the airplane. On my Hawk I've found it to be just fine - no discernable visual distortion, very lightweight. I'm considering making a bag for behind the seat to keep the doors for those days (or fly-ins) where I might change my mind about having the doors on.

I have found that the doors bell in a bit in flight due to the airstream, maybe an inch or two. Hasn't been a problem at all. Note that it's a double-headed zipper, starting at the leading edge of the door and joining at the top back of it, which allows opening the top and back for ventilation.

Cockpit Bracing and Instrument Pod

Locate a horizontal strut at the elevation at the elevation of the instruments. This bar will span the cockpit from side to side. In the middle of it will be a strut going down to the lower tube. This 'T' assembly will support the instruments and also act as supporting for the mid points of the sides of the cockpit.

At back top of fuselage the struts to the two masts must be connected to the top of the seat back. The fuel tank canbe part of the fuselage or power train.

Last Revised: May 13, 2008